This invention relates to catalytic hydrocarbon processing, and particularly to hydrocarbon hydroprocessing, such as the process involving catalyzing the reaction of hydrogen with aromatic compounds. More particularly, this invention is directed to a process for saturating aromatic compounds in hydrocarbon liquids.
During the course of catalytic refining of hydrocarbons, heterocyclic compounds, including oxygen compounds, are removed from hydrocarbon oil. Aromatic compounds contained in the hydrocarbon oil are also contacted during the refining process with a catalyst in the presence of hydrogen, causing conversion of such aromatic compounds to more saturated forms, i.e., the aromatic compounds are hydrogenated.
Economic considerations have provided new incentives for catalytic conversion of the aromatic fractions to more marketable products. Today there is a steadily increasing demand for relatively non-aromatic middle distillate products boiling in the range of about 300.degree.-700.degree. F. Such products include, for example, aviation turbine fuels, diesel fuels, solvents and the like. Products in this boiling range are conventionally produced by the hydrotreating and/or hydrocracking of various refinery streams boiling in or above the desired product range. Hydrotreating and hydrocracking operations generally effect a substantial partial hydrogenation of polycyclic aromatics, but the resulting products still contain a relatively high percentage of monoaromatic hydrocarbons. Further hydrogenation of these products is desired in many cases to produce acceptable solvent products or to meet specifications (smoke point and luminometer number) for jet fuels, (cetane number) for diesel fuels, etc.
Accordingly, a need still exists for an improved process for reducing the content of aromatic hydrocarbon compounds to specified levels in a product hydrocarbon oil. It is, therefore, a major object of the present invention to provide a process for saturating aromatic compounds in a hydrocarbon oil, and more specifically to provide a hydrogenative catalytic aromatic saturation process while simultaneously hydrocracking a substantial proportion of the hydrocarbon oil.
It is another object of the invention to provide a multi-reaction zone process for the catalytic saturation of aromatic compounds in a hydrocarbon oil, and more specifically to provide a process for substantially hydrogenating an aromatic-containing hydrocarbon oil to obtain improved products of low aromatic content.
A further object of the invention is to provide hydrocarbon products of reduced aromatic content in a process utilizing less refining catalyst.
These and other objects and advantages of the invention will become apparent from the following description.